This is a case-control study of 225 cases and matched controls resident in New Jersey. All males between the ages of 25 and 64 years with a diagnosis of malignant melanoma who were first diagnosed between October 1, 1978 and December 30, 1980 and resided in New Jersey, will be eligible as cases. Controls will be matched for age, race and area of residence. Information from private dermatopathology laboratories and hospital pathologist records will be used to determine cases aided by the New Jersey and New York cancer registries. All cases will be ascertained as malignant melanoma by a board of certified dermatopathologists. Home interviewing of cases and controls will obtain information on: residence history, work exposure history, (particularly to chemical substances), sun exposure, history of cancer in the family and history of chloracne dermatitis. Preliminary work has provided suggestive evidence of a large relative risk of malignant melanoma among workers exposed to polyclorinated biphenyls (PCBs) and other chemicals. New Jersey has the largest number of workers in chemical and related industries in the nation and high melanoma mortality rates (for an area outside of the South) among males. Investigation will be carried out to determine if there are significant differences between cases and controls in exposure to chemical substances, exposure to sunlight, or a previous history of chloracne dermatitis. This proposal is to extend the two year study currently underway to a third year.